This invention relates generally to molecularly polarized polymer materials and in particular to techniques for forming molecularly polarized polymer materials into non-planar shapes.
As is known in the art, certain polymer and co-polymer materials may be provided with piezoelectric properties. For example, sheets of a polymer material comprising polyvinylidenefluoride having long repeating chains of CH.sub.2 --CHF.sub.2 molecules can have these chains orientated to provide a net polarization. Such material when provided with conductive electrodes over opposing surfaces thereof have piezoelectric properties which make them suitable for transducers. Such transducers have important applications in the generation and reception of acoustic energy.
In certain applications for such transducers such as in towed sonar arrays, the generally used flat sheets of PVDF are not the optimum shape. It would be desireable to have such sheets of PVDF preformed into some specific shape, such as a dome, a hemi-cylindrical section, or a rod.
One technique suggested in the art for providing non-planar shaped layers of molecularly polarized polymers includes the use of plastic extrusion techniques. That is, a coat of polymer material may be deposited over a wire by extruding the polymer material onto a member which is drawn through or passed by the extruder. A second technique is a cold forming technique in which a sheet of molecularly polarized polymer material is bent into a desired position and clamped or otherwise held into position forming a non-planar shape.
Nevertheless, it would be desireable to provide various non-planar shapes of polyvinylidenefluoride materials. In particular, it would be desireable to provide a technique for forming such shapes after the polyvinylidenefluoride has been polarized. Moreover, it would be desireable to provide permanent shapes of such material to eliminate the need for extensive clamping, for example, as required in the cold-forming technique and, furthermore, to provide a variety of shapes rather than those limited by the extrusion process.